1. Field of the Invention
The present invention relates to an apparatus and a method for reducing power consumption in a portable terminal that transmits digital broadcast data through an ad hoc network. More particularly, the present invention relates to an apparatus and a method for buffering received data in a portable terminal and transmitting the buffered data after maintaining a sleep state for a predefined time.
2. Description of the Related Art
Recently, portable terminals have become necessities to many people without distinction of age and gender, and service providers and terminal manufacturers are competitively developing products (or services) for differentiation from other enterprises.
For example, portable terminals have evolved into multimedia devices that can provide various functions and services including any or all of phone book functions, game functions, a Short Message Service (SMS), an Electronic (E)-mail services, morning call functions, Motion Picture Expert Group Audio Layer-3 (MP3) functions, scheduling functions, digital camera functions, multimedia message services, wireless Internet services, and the like.
WiFi terminals with a wireless Local Area Network (LAN) function have recently been released. The WiFi terminals with a wireless LAN function are used to access e-mail, Web and string media. WiFi provides a wireless broadband Internet access service to users, thus making it possible to rapidly and conveniently access an on-line network during movement as well as at home and office.
The WiFi network may be divided into an ad hoc network, which provides direct communication between WiFi terminals without passing through an Access Point (AP), and an infra network based on the AP.
When a terminal with a digital broadcast receiving module and terminals without a digital broadcast receiving module are connected through an ad hoc network to each other, the terminal with a digital broadcast receiving module transmits broadcast data to the terminals without a digital broadcast receiving module, thereby enabling the sharing of the digital broadcast.
Because the ad hoc network does not provide an AP, each of the terminals generates/transmits a beacon notifying the existence of a network. When approaching the Target Beacon Transmission Time (TBTT), the terminals generate a beacon after a random delay time.
That is, the terminals wake up at the TBTT to monitor a physical channel of the ad hoc network for a random delay time set in each terminal. The terminal immediately cancels the beacon transmission if another terminal generates a beacon before it transmits a beacon.
When a beacon interval starts, the terminals wake up for an Announcement Traffic Indication Message (ATIM) window interval to transmit a beacon frame. If there is data communication between transmitting/receiving terminals, the terminals must maintain a wake-up state. On the other hand, if there is no data communication between the transmitting/receiving terminals, the terminals enter a sleep mode for the remaining interval except an ATIM window in the beacon interval, thus minimizing the power consumption.
As described above, if the terminal receives a TeleVision (TV) channel through an ad hoc network and immediately retransmits the same to a receiving terminal, it continuously receives several mixed broadcast channels. Therefore, if the broadcast data are retransmitted thorough WiFi, there is no period to stop the operation of a receiver. Accordingly, it cannot enter a sleep mode until the completion of transmission of digital broadcast data, thereby increasing the power consumption.
Therefore, a need exists for an apparatus and a method for reducing power consumption in a portable terminal that transmits digital broadcast data through an ad hoc network.